As angular velocity sensors for consumer use, vibration-type gyro sensors are widely used. The vibration-type gyro sensor detects an angular velocity by causing a vibrator to vibrate at a predetermined frequency and detecting a Coriolis force caused in the vibrator using a piezoelectric device and the like. The gyro sensors are mounted on electronic apparatuses such as a video camera, a virtual reality apparatus, and a car navigation system and used as sensors for hand-movement detection, operation detection, direction detection, and the like.
In recent years, along with miniaturization and technical advancement in performance of electronic apparatuses, miniaturization and technical advancement in performance of gyro sensors that are to be mounted on those electronic apparatuses are being demanded. For example, for realizing miniaturization of gyro sensors, a technology called MEMS (Micro Electro Mechanical System) is generally used as described in Patent Document 1. Specifically, Patent Document 1 discloses an angular velocity sensor including three arm portions formed by performing microfabrication on a silicon substrate, a piezoelectric film formed on a front surface of each of the arm portions, an vibration driving electrode formed on the piezoelectric film of each of the two arm portions positioned on an outer side, and a detection electrode for detecting angular velocities, that is formed on the piezoelectric film of the center arm portion.
Patent Document 1: Japanese Patent Application Laid-open No. 2008-256669